l2tp: constify net_device_ops structures

Check for net_device_ops structures that are only stored in the netdev_ops
field of a net_device structure. This field is declared const, so
net_device_ops structures that have this property can be declared as const
also.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@r disable optional_qualifier@
identifier i;
position p;
@@
static struct net_device_ops i@p = { ... };

@ok@
identifier r.i;
struct net_device e;
position p;
@@
e.netdev_ops = &i@p;

@bad@
position p != {r.p,ok.p};
identifier r.i;
struct net_device_ops e;
@@
e@i@p

@depends on !bad disable optional_qualifier@
identifier r.i;
@@
static
+const
struct net_device_ops i = { ... };
// </smpl>

The result of size on this file before the change is:
text data bss dec hex filename
3401 931 44 4376 1118 net/l2tp/l2tp_eth.o

and after the change it is:
text data bss dec hex filename
3993 347 44 4384 1120 net/l2tp/l2tp_eth.o

Signed-off-by: Julia Lawall <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/l2tp/l2tp_eth.c

···
 }
 
 
-static struct net_device_ops l2tp_eth_netdev_ops = {
+static const struct net_device_ops l2tp_eth_netdev_ops = {
 	.ndo_init		= l2tp_eth_dev_init,
 	.ndo_uninit		= l2tp_eth_dev_uninit,
 	.ndo_start_xmit		= l2tp_eth_dev_xmit,